672 DEScriPTioN of IRoiatoria. 



Genus Monolabis. — Tlicso Pkilodinean Rotatoria have two frontal 

 red eyes, and a foot with two toes, but no horn-like processes. They 

 are provided with muscles for moving the double rotatory apparatus, 

 two for moving the foot, and four belong to the oesophageal head 

 and jaws, which last are furnished with double teeth, or teeth in 

 rows. A very short oesophageal tube, and a simple conical alimen- 

 tary^ canal, are seen in both species, one of them has two spherical 

 biliary glands; an ovarium is seen in both, but in neither have fully- 

 developed ova or male organs been observed. In one species, a 

 respirator}' tube is present. 



M. conica. — Body stout, provided with a respiratory tube, or spur, 

 and three teeth in each jaw. Between the rotatory organs the brotv 

 can project and resemble a proboscis. Figures 485, 486, represent 

 different views from the under side. Length 1 -120th. 



M. gracilis. — Has a more slender body than the last, and two teeth 

 in each jaw, but no respiratory tube or spur. Length about 1 -200th. 



Genus Philodina. — Tlie necked Rotatoria have two cervical eyes, 

 and horn-like processes to the foot. All the species possess two 

 vibratUe or wheel organs upon the breast, and five of them have a 

 frontal ciliated proboscis. Longitudinal muscles are distinct in one 

 species, and two for moving the foot in six. The oesophageal head 

 has four muscles ; its jaws are two-toothed in four species, three- 

 toothed in two species; but in one species the oesophageal head 

 lias not been satisfactorily seen. The alimentary canal is filiform, 

 with a posterior enlargement in six species ; in one it appears to have 

 pouches or pockets. The glandular or cellular mass surrounding the 

 filiform part of the canal sometimes becomes distinctly coloured when 

 the creature eats coloured food, and therefore seems corinected wdth 

 tlie nutritive system, and is probably a convolution of ccecal appen- 

 dages. Biliary glands are found in six sj^ecies. The ovarium deve- 

 lopes eggs, but very seldom living young, hence they are only 

 occasionally viviparous ; three species possess a contractile vesicle ; 

 one, sexual glands. A respiratory tube at the neck is always present, 

 in some cases it is ciliated. Transverse vessels are seen only in P, 

 erythropthalma. Eyes are found in all the species, and nervous gang- 

 lia connected with them in P. erythropthahia ; sometimes the eyes 

 arc very pale, Ikjucc a single specimen may be mistaken for Callidina. 



